Pre-stretched process for ADSS optical cable in Congo

The pre-stretched (pre-twisted) process for ADSS optical cables involves using preformed armor rods and tension clamps to protect the cable while suspending it on overhead lines, ensuring uniform stress distribution and preventing damage from high-voltage effects.Pre-Twisted Strain Clamp and Armor RodsADSS optical cables are installed using pre-twisted or preformed strain clamps, which consist of inner and outer preformed armor rods. The inner rods are typically made of high-molecular polymer materials resistant to electrical tracking, bonded with monofilaments and coated with white corundum to prevent abrasion and electrocorrosion under high-voltage conditions . The outer rods are often aluminum-clad steel, grouped to enhance mechanical strength while reducing stress on the cable . This configuration increases the contact area with the cable, distributing tension evenly and protecting the optical fibers from mechanical damage.Installation MethodsTwo main methods are used for stringing ADSS cables:Stationary Reel Method: The cable reel is fixed at one end, and a pull line threads through travelers to the take-up reel at the other end. The ADSS cable is attached to the pull line using a woven wire pulling eye, ensuring controlled tension and minimal bending .Controlled Paying-Off Method: During installation, the cable is carefully paid off from the reel under stable tension, avoiding exceeding the rated pulling tension. Pulleys with diameters of 400–600 mm, lined with elastic buffer materials, are recommended to prevent cable rotation and fiber damage .Safety and Environmental ConsiderationsADSS cables are non-metallic and can be installed on live lines, but personnel must follow local power industry safety regulations and use insulated tools and safety belts .The cable's minimum dynamic bending radius should be at least 20 times the cable diameter to prevent fiber breakage.Ends of the cable must be sealed with waterproof adhesive tape to prevent moisture ingress, which can increase attenuation or cause fiber breakage .Pre-twisted clamps prevent corona discharge and electrocorrosion, which is critical in high-voltage lines like 220 kV circuits .Material and Hardware SelectionInner preformed rods: Polymer composite, anti-electric tracking, coated with fused alumina.Outer rods: Aluminum-clad steel for mechanical strength.Thimble clevis and anchor shackles: Hot-dip galvanized steel, selected based on failure load requirements (20–120 kN) for secure attachment .Pulling ropes: Aramid yarn or nylon with PE covering for high strength and low elongation.SummaryThe pre-stretched or pre-twisted process in Congo involves using preformed armor rods and tension clamps to suspend ADSS cables safely on overhead lines. This method ensures uniform stress distribution, protection against abrasion and electrical effects, and compliance with local safety standards. Proper installation requires careful attention to tension control, bending radius, and environmental protection to maintain long-term cable performance.